Hardi ISOBUS VT, Operator'S Manual

Page: 54 / 104

7 - Menu 3 Calibration
7.2
Menu 3.1.1.1 Sprayer speed constant
The theoretical speed constant, pulses per unit (PPU), is the number of
times the speed sensor records holes (or protrusions / magnets) per foot
(meter) as the wheel rotates past the sensor. If necessary, this can be
calculated by dividing the number of protrusions by the circumference
of the tire in feet (meters).
By using known tire dimensions and number of protrusions, the
following formulas may be used to calculate the theoretical PPU:
PPU (feet)
PPU (meter)
Example
If changing tires on a Commander 7000 (36 protrusions) to a 320/90R50 tire, the PPU (feet) is calculated as follows:
˜
ATTENTION! The practical method is recommended.
Menu 3.1.1.2 Sprayer speed practical
Practical calibration of speed is done by driving a measured distance
and correcting the display so that the actual and the calculated
distances are the same.
÷
NOTE! Calibration should take place in the field with a half full
tank and normal working tire pressure in order to obtain the
wheel’s real “working radius”.
˜
ATTENTION! Changing tires will require a new calibration!
Method
1.
Measure a distance not less than 200 feet.
2.
Park the tractor at the start of the measured distance.
3.
Press Enter. When zero distance [0] shows, drive the distance.
4.
Press Enter.
5.
Correct the distance shown on the display to read the actual distance.
6.
Press Enter to see the new calculated value.
7.
Press Enter again to accept the value.
8.
Repeat process to verify calibration. PPU should not change significantly if calibration has been made correctly.
PPU
Protrusions 12
×
π
Tirewidth Ratio
×
1270
----------------------------------------------
Rimheight
+
¹
·
©
§
×
-------------------------------------------------------------------------------------------------
=
PPU
Protrusions 1000
×
π
Tirewidth Ratio
×
50
----------------------------------------------
Rimheight 25.4
×
+
¹
·
©
§
×
-----------------------------------------------------------------------------------------------------------------
=
PPU
36 12
×
3.14159
320 90 ×
1270
--------------------- 50
+
© ¹
§ ·
×
-----------------------------------------------------------------
1.892
= =